The Nationals made a trade to improve their bullpen. But who will close?

Ben Margot / AP

Athletics reliever Sean Doolittle during a game against the Tigers in 2016.

Athletics reliever Sean Doolittle during a game against the Tigers in 2016.

(Ben Margot / AP)

Jorge CastilloThe Washington Post

The Nationals addressed a glaring weakness Sunday, acquiring relievers Ryan Madson and Sean Doolittle from the Athletics. It was only a matter of time before something was done to strengthen a relief corps that is sporting the highest bullpen ERA in the majors. With the addition of Madson and Doolittle, the Nationals' bullpen is undeniably better, a substantial development in the baseball landscape for a team that already boasted one of the league's best offenses and starting rotations. That they didn't surrender one of their top four prospects makes it sweeter.

But two questions remain: Who will close games in October? And will General Manager Mike Rizzo make another trade to bolster the bullpen before the July 31 non-waiver deadline? The two may be connected.

After Sunday's drubbing of the Reds, Rizzo and manager Dusty Baker both said they're not sure who will assume the closer role once the acquisitions join the team, which could be Monday in Cincinnati or Tuesday in Anaheim. Doolittle or Madson will close games. That, it seems, is certain. Baker said perhaps both could do it, though he has bluntly voiced skepticism in closer-by-committees this year. He said he planned on asking Athletics Manager Bob Melvin how he used them. Rizzo, on the other hand, said he envisions one of them getting the job.

"I think that Dusty will stabilize the bullpen and set on one guy," Rizzo said. "And kind of get a little rhythm back there and get guys comfortable in their roles."

Both have closed games. Madson, who turns 37 next month, has 86 career saves. He converted 30 of them last season for Oakland. He was primarily a setup man for the Athletics this season. He notched just one save and finished eight games, while compiling a 2.06 ERA, 0.788 WHIP, and he gave up just two home runs in 39 1/3 innings.

Doolittle has less experience in the role, but has saved 36 games in his six major league seasons. The 30-year-old left-hander compiled 22 in 2014, when he made his only all-star team and pitched to a 2.73 ERA. This year, he's finished six games and posted a 3.38 ERA across 21 1/3 innings.

"It's nice to have guys who have done it before, guys who have pitched in big games and pitched in playoff games," Rizzo said. "That had a lot to do with [making the trade]. I think the ability and the stuff was important to us. They performed great throughout their careers, they performed really well this year. One's left-handed, one's right-handed. That gives us a little bit more balance in the bullpen. They both capable of getting out both lefty and right-handed hitters. So they're very versatile, no egos, they're capable of pitching in the eighth or ninth inning. They've both done it."

The Nationals can stand pat with the two new pieces, add Koda Glover when he comes off the disabled list, maybe bring up top prospect Erick Fedde later in the season and enter the playoffs with a vastly improved relief corps. Or they could continue the bullpen makeover with another trade, perhaps acquiring a proven closer to solve the first question. The trade market doesn't feature the glut of top-notch closers that last year's did. Orioles left-hander Zach Britton might be the best available. The Nationals reportedly expressed interest in the left-hander, but the neighbors' contentious relationship impeded negotiations.

There are, however, other options out there that could help. White Sox closer David Robertson is still available, though he might be too expensive now that the Nationals have taken on considerable money with Doolittle and Madson. Pat Neshek, Brad Hand, Justin Wilson and A.J. Ramos remain obtainable, too. The Nationals were reportedly discussing Ramos and David Phelps with the Marlins before shifting their focus to Doolittle and Madson.

So there are options. The Nationals have two weeks to evaluate them, and themselves, and decide.

"I think we've done what we came to do at the trade deadline," Rizzo said. "That's not to say that we're going to stop scouting. As we've shown in the past, if there's an opportunity to improve the ballclub, we'll certainly continue to be aggressive and try to help us out any way we can."